code: def testStringAggregation(self):
      p = Pool({"foo": ["foo", "bar"]})
  
      results = PoolAggregator()(p)
  
      self.assertEqualVector(results["foo"], ["foo", "bar"])
      self.assertEqualVector(results.descriptorNames(), ["foo"])
  
file_path: essentia/test/src/unittests/stats/test_poolaggregator.py
imports: from essentia_test import *
label_desc: Use image node_id 3 for calling the TestPoolAggregator obj's underlying member method code with example usage: obj.testStringAggregation() without return types